I accidentally filled out my Turbo Tax Extension wrong and put my total estimated gross income where total estimated taxes owed would go. How do I fix this?

You can wait to see if your extension gets rejected or accepted. If your extension is rejected then you can fix it with correct information; otherwise, you can correct it when you go back to TurboTax to file your tax return and make sure to enter the correct payment you already made if that's the case. TurboTax will take into consideration of the tax payment you already made. If you still have question about it, make sure to contact TurboTax Support https://support.turbotax.intuit.com/contact/

Unfortunately, you can't amend an extension request that's already been accepted by the IRS.

However, if your e-filed your extension is rejected by the IRS, you can make any changes before you resubmit it, or mail it in.